Integrated energy system for whole home or building

ABSTRACT

An integrated energy system for a home or other building utilizes a heated reservoir for energy storage. The reservoir is mainly heated by one or more solar collectors. The system also includes an environment-coupled piping loop through which a cooling fluid is circulated such that heat is exhausted from the cooling fluid to the environment. The thermal energy from the reservoir and the cooling fluid are then used in an integrated set of systems that provide space heating, space cooling, and electrical generation. Electricity is generated by a thermoelectric generator that exploits the temperature differential between the reservoir and the cooling fluid. The system may include heating and storage for domestic hot water, and may use excess power for hydrogen production. Backup heating and electrical systems may be provided for.

This application claims priority to provisional application 61/060,377,filed Jun. 10, 2008 and titled “Combined Heat and Power and HydrogenGeneration for Whole Home or Building with Ground Heat Exchanger UsingThermoelectric Seebeck Modules,” the entire disclosure of which ishereby incorporated by reference herein for all purposes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No. ______(Attorney docket number 027483-000300US), titled “AutomaticConfiguration of Thermoelectric Generation System to Load Requirements”and to U.S. patent application Ser. No. ______ (Attorney docket number027483-000500US), titled “Thermoelectric Generator”, both having thesame inventor as the present application and filed Jun. 10, 2009. Thedisclosures of those two applications are hereby incorporated herein intheir entirety for all purposes. Provisional U.S. patent application60/306,274, titled “Combination outdoor portable heating pad andelectricity generator” is also hereby incorporated by reference hereinfor all purposes.

BACKGROUND OF THE INVENTION

A typical home or other building includes several energy systems. Forexample, the building maybe connected to the mains power grid andreceive electrical power generated at a remote power plant. The buildingmay be supplied with natural gas for space and water heating. Many ofthese traditional energy systems depend on non-renewable andever-more-expensive fossil fuels.

Alternative energy systems have been proposed. However, prioralternative energy systems have evolved piecemeal. Furthermore, manyalternative electrical systems rely on photovoltaic cells to generateelectricity from sunlight, and store the resulting electrical energy inbatteries. While the day-to-day operating cost of a photovoltaic systemis low, these systems typically have a high installation cost, and thebatteries have a finite life, requiring expensive periodic replacements.Battery systems also are typically oversized, as the life of thebatteries is optimized by avoiding discharges of more than 20 percent ofthe stored energy from the batteries.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, an integrated energy system for a building comprisesat least one reservoir of thermal energy, at least one solar collectorthat provides heat to the reservoir, and at least oneenvironment-coupled piping loop through which a cooling fluid iscirculated such that heat is exhausted from the cooling fluid to theenvironment. The system further comprises a thermoelectric generatorthat generates electric power from a temperature differential betweenthe reservoir of thermal energy and the cooling fluid, and at least onehydronic heating unit through which heated fluid is piped, providingspace heating to at least one space in the building, the heated fluidderiving its heat from the reservoir of thermal energy. The system mayalso comprise at least one hydronic cooling loop through which at leastsome of the cooling fluid is piped, providing space cooling to at leastone space in the building. In some embodiments, the system furthercomprises a backup heater that provides heat to the reservoir of thermalenergy, supplementing the solar collector. The backup heater may deriveheat from a fossil fuel.

In some embodiments, the system comprises a tank of hot water designatedfor domestic hot water use. The system may further comprise a backupdomestic water heater that supplies heat to water designated fordomestic hot water use when insufficient energy is otherwise available.The backup domestic water heater may comprise at least one on-demandheater. The backup domestic water heater may derive heat from a fossilfuel.

In some embodiments, the system further comprises a direct-current powergrid within the building. In some embodiments, the system includes aninverter that converts direct-current power from the thermoelectricgenerator to alternating-current power.

In some embodiments, the thermoelectric generator comprises a pluralityof banks, and the integrated energy system further comprises athermoelectric generator controller and a matrix switch that, undercontrol of the thermoelectric generator controller, configures theinterconnection of the banks.

In some embodiments, the system further comprises a load controller thatat least temporarily prevents the operation of at least one load basedin part on the amount of electrical power being consumed by other loads.In some embodiments, the system comprises a backup connection to themains power grid, the backup connection providing electrical power tothe building to supplement the thermoelectric generator.

In some embodiments, the system includes a hydrogen generator powered byelectricity from the thermoelectric generator. The system may alsoinclude a backup domestic water heater, wherein the backup domesticwater heater derives heat from hydrogen generated by the hydrogengenerator.

In some embodiments, the reservoir of thermal energy comprises a tank ofheated water. A medium in the reservoir of thermal energy may be heateddirectly by the solar collector. The medium in the reservoir of thermalenergy may be heated though a heat exchanger carrying a second mediumheated by the solar collector.

In some embodiments, the heated fluid circulated through the at leastone hydronic heating unit derives its heat from the reservoir of thermalenergy through a heat exchanger. The at least one environment-coupledpiping loop may comprise a deep earth-coupled piping loop. The at leastone environment-coupled piping loop may comprise a shallow earth-coupledpiping loop. The at least one environment-coupled piping loop maycomprise an air-coupled piping loop.

In another embodiment, a method of operating an energy system in abuilding comprises, heating a reservoir of thermal energy using a solarcollector. Heated fluid that derives its heat from the reservoir ofthermal energy is circulated through a hydronic heating loop, providingspace heating to at least one space in the building. A cooling fluid iscirculated through an environment-coupled piping loop such that heat isexhausted from the cooling fluid to the environment, and electricalpower is generated a thermoelectric generator subjected to a temperaturedifferential between reservoir and the cooling fluid.

In some embodiments, the method further comprises circulating at leastsome of the cooling fluid through a hydronic cooling loop, providingspace cooling to at least one space in the building. The method maycomprise generating hydrogen using electrical energy generated by thethermoelectric generator. In some embodiments, the method comprisesstoring, separately from the reservoir of thermal energy, waterdesignated for domestic hot water use. In some embodiments, the methodfurther comprises heating the water designated for domestic hot wateruse with heat from the reservoir of thermal energy. In some embodiments,the method comprises dynamically configuring, using a thermoelectricgenerator controller, interconnections of thermoelectric modules withinthe thermoelectric generator. In some embodiments, the method comprisestemporarily preventing the operation of at least one electrical loadbased in part on the amount of electrical power being consumed by otherloads. In some embodiments, circulating the cooling fluid through andenvironment-coupled piping loop comprises circulating the cooling fluidthrough and earth-coupled piping loop.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an integrated energy system for a building in accordancewith a first embodiment.

FIG. 2 shows a portion of the system of FIG. 1 in greater detail, inaccordance with another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

An integrated energy system for a home or other building utilizes aheated reservoir for energy storage. The reservoir is mainly heated byone or more solar collectors. The system also includes at least oneenvironment-coupled piping loop through which a cooling fluid iscirculated such that heat is exhausted from the cooling fluid to theenvironment. The thermal energy from the reservoir and the cooling fluidare then used in an integrated set of systems that provide spaceheating, space cooling, and electrical generation. Electricity isgenerated by a thermoelectric generator that exploits the temperaturedifferential between the reservoir and the cooling fluid. The system mayinclude heating and storage for domestic hot water, and may use excesspower for hydrogen production. Backup heating and electrical systems maybe provided for.

The ensuing description provides preferred exemplary embodiment(s) only,and is not intended to limit the scope, applicability or configurationof the disclosure. Rather, the ensuing description of the preferredexemplary embodiment(s) will provide those skilled in the art with anenabling description for implementing a preferred exemplary embodiment.It being understood that various changes may be made in the function andarrangement of elements without departing from the spirit and scope asset forth in the appended claims.

Specific details are given in the following description to provide athorough understanding of the embodiments. However, it will beunderstood by one of ordinary skill in the art that the embodiments maybe practiced without these specific details. For example, circuits maybe shown in block diagrams in order not to obscure the embodiments inunnecessary detail. In other instances, well-known circuits, processes,algorithms, structures, and techniques may be shown without unnecessarydetail in order to avoid obscuring the embodiments.

Furthermore, embodiments may be implemented by hardware, software,firmware, middleware, microcode, hardware description languages, or anycombination thereof. When implemented in software, firmware, middlewareor microcode, the program code or code segments to perform the necessarytasks may be stored in a machine readable medium. A processor(s) mayperform the necessary tasks.

Prior alternative energy systems have evolved piecemeal. For example, ina typical “solar” home, electricity generation is provided byphotovoltaic cells with battery storage, while domestic hot water isprovided by direct solar heating of water. Space heating may be enhancedby passive solar design techniques, with supplemental backup provided byburning natural gas, propane, wood, or another fuel. Space cooling mayor may not be provided. This piecemeal approach to building energymanagement is complex and involves many different technologies.Electricity generation by photovoltaics requires different solarcollectors than those used for water heating, and requires expensivebatteries that require periodic replacement. The batteries are typicallyoversized, in order to maximize their useful life by avoiding deepdischarges.

Embodiments of the present invention exploit efficiencies made possibleby integrating the various energy systems in a building. A single solarcollector (or collector array) heats a reservoir of thermal energy. Thereservoir of thermal energy may be a simple tank of heated water thatstores thermal energy by virtue of the elevated temperature of thewater. In other embodiments, the reservoir of thermal energy maycomprise another medium, for example a eutectic or phase change mediumsuch as Glauber's salt that stores energy primarily in the change of thesalt between solid and liquid phases.

The reservoir of thermal energy is used for multiple purposes in thesystem. The thermal energy may be used directly for space and domesticwater heating. Electricity generation is provided by a thermoelectricgenerator, using the elevated temperature of the reservoir as the “hot”side of a temperature differential exploited by the thermoelectricgenerator. The other “cold” side of the temperature differential isprovided by a cooling fluid, preferably water, circulated through anenvironment-coupled piping loop that cools the fluid via its thermalcontact with the earth or atmosphere. The cooling fluid may also be usedfor hydronic space cooling.

The advantages of such a system will be apparent to one of skill in theart. Energy storage is provided by a single reservoir, which may be assimple as a tank of water. No harsh or dangerous chemicals are neededfor energy storage, and no expensive battery replacement is ever needed.Space heating, domestic water heating, and electrical generation arepowered by a single solar collector or array of collectors. Spacecooling comes as a by-product of electrical generation. Such a system issimpler, less expensive, and more flexible than the traditionalpiecemeal approach to alternative energy systems.

FIG. 1 shows an integrated energy system 100 for a building 109 inaccordance with a first embodiment. In example system 100, a solarcollector 101 heats fluid in a tube 103, using energy from the sun 104.In this example, solar collector 101 is a concentrating type solarcollector, for example a parabolic trough that concentrates solarradiation on tube 103 and tracks the motion of the sun under control ofa motor 102. One of skill in the art will recognize that other kinds ofsolar collectors may be used, including flat panel collectors or heatpipe collectors. One collector or an array of collectors may be used,depending on the design capacity of the system. At present, many squaremeters of collector area may be needed to provide sufficient electricalgeneration capacity in system 100, but it is anticipated that futureimprovements in the efficiency of thermoelectric materials will reducethe required collector area dramatically.

The fluid in tube 103 is heated and is circulated by a pump (not shown),carrying thermal energy to a reservoir of thermal energy 105. Theworking fluid in tube 103 may be water, a natural or synthetic oil, oranother kind of fluid. Reservoir 105 contains a storage medium. Themedium may simply be water. If water from reservoir 105 is alsocirculated through tube 103, then the water is heated directly by solarcollector 101. Alternatively, the medium in reservoir 105 may be heatedindirectly, for example through a heat exchanger. For example, if theworking fluid in tube 103 is an oil and the storage medium in reservoir105 is water, the water may take heat from the oil through a heatexchanger. If the storage medium in reservoir 105 is water, it isestimated that a 1000 gallon reservoir will be sufficient for a typicalresidential application. Preferably, the pump circulating the fluid intube 103 operates only as necessary to maintain the temperature ofreservoir 105. For example, the pump may be turned off at night when noeffective fluid heating is available from solar collector 101.

The storage medium in reservoir 105 may be another kind of medium. Insome embodiments, the medium in reservoir 105 may be a phase-changemedium such as Glauber's salt, which efficiently stores thermal energyby virtue of a phase change from solid to liquid. Other media, includingother phase change media, may be used.

Reservoir 105 provides simple, reliable, maintenance free energy storagefor the system. The storage medium need not be changed or serviced, aswould be the case with batteries.

Thermal energy from reservoir 105 may be used directly or indirectly forvarious heating needs in the building. For example, if the medium inreservoir 105 is water, water could be drawn from reservoir 105 fordomestic hot water use. In that case, reservoir 105 would be replenishedwith additional supply water as needed to replace that drawn off foruse. For the purposes if this disclosure, “domestic hot water” is heatedwater used for washing, bathing, cooking, or other processing or thelike, whether system 100 is installed in a home, business, or industrialsetting. Domestic water is typically discarded to a sanitary sewer afteruse. “Supply water” is water from an external water supply, such as amunicipal water utility, a local well, or other source.

Preferably, especially where a medium other than water is used inreservoir 105, domestic hot water may be heated from reservoir 105 byuse of a heat exchanger, and optionally may be stored in a separate tank106. Separate storage with independent temperature control may beadvantageous because domestic water should be stored within a narrowtemperature range for safety and utility reasons. The medium inreservoir 105 may undergo large temperature fluctuations duringoperation of system 100, and may reach temperatures that would be unsafefor domestic hot water use.

A similar arrangement may be used for water used for space heating.Water from reservoir 105 may be circulated to a hydronic heating loop107 that may include baseboard, subfloor, valence or other piping andfixtures that provide heat to spaces in the building primarily throughconvection, radiation, or both. Alternatively, the fluid circulatedthrough hydronic heating loop 107 may derive its heat from reservoir 105through a heat exchanger. Optionally, a separate storage tank 108 may beprovided for the water or other fluid used for hydronic heating,enabling separate temperature control. In some embodiments, the fluidused for hydronic heating may be a fluid other than pure water, forexample a water and antifreeze mix.

Optionally, backup heating may be provided to one or more of the heatedreservoirs in the system, including any one, any combination, or all ofreservoir 105 and any additional storage tanks such as tanks 106 and107. Backup heating may be in the form of a boiler or other kind ofheater that burns fossil fuel, or may be another kind of heater. Backupheating may be required during extended periods without adequate sun tomaintain a sufficient temperature of reservoir 105, or during times whentemporary guests increase the energy demands of building 109.

If backup heating is supplied to reservoir 105, then a single backupheater may be sufficient. Alternatively, separate backup heating unitsmay be provided for domestic hot water tank 106 and space heatingstorage tank 108, if they are present. In yet another attractivealternative, backup heating for domestic hot water may be an “on demand”type heater that heats water only as it is used, rather than maintaininga tank of hot water at a specified temperature. An on-demand heater maybe placed at a central location and heat water for domestic hot wateruse throughout the building, or multiple on-demand heaters may be placedat the various points of use of hot water, such as one in each bathroomand kitchen.

In another aspect of system 100, water or another fluid is circulated bya pump (not shown) through an environment-coupled piping loop such asdeep earth-coupled piping loop 110. Deep earth-coupled piping loop 110cools this “cooling fluid” by virtue of its thermal contact with theearth. Heat is exhausted from the cooling fluid to the earth, therebymaintaining the cooling fluid at a relatively cold temperature. Atsufficient depths, usually about five feet (1.6 m) or more below thesurface, the earth maintains a relatively constant temperature, forexample about 54-57° F. (12-14° C.) in many parts of the United States.Alternatively or additionally, other environment-coupled piping loopssuch as shallow earth-coupled piping loop 122 or air-coupled piping loop123 may be used as described in more detail below. Optionally, a storagetank 111 for some of the cooling fluid is provided. The cooling fluidmay also be used for multiple purposes. In one use, some of the coolingfluid is circulated as needed through a hydronic cooling loop 112 thatmay include baseboard, subfloor, valence or other piping and fixturesthat remove heat from spaces in the building primarily throughconvection, radiation, or both. It is estimated that 1000 feet of tubingcoiled in a trench 100 feet long can provide one ton (12,000 BTU/hr, or3.516 kW) of cooling capacity. Vertical cooling wells can be used tosave space, but at a slightly higher installation cost. Preferably, thepump circulating the cooling fluid operates only as needed to maintain arelatively cold temperature in the fluid supplied to hydronic coolingloop 112, and for electricity generation as described below. Typically,fluid will be circulated through only one of hydronic cooling loop 112and hydronic heating loop 107 at any one time.

Generation of electricity is provided by a thermoelectric generator 113.A thermoelectric generator generates electrical power from a differencein temperature using the thermoelectric effect exhibited by manymaterials. A typical thermoelectric generator comprises manythermoelectric elements arranged in thermoelectric couples. Eachthermoelectric element may be a conductive or semiconductive element,for example pieces of n-type and p-type semiconductor material. Theelements are connected electrically in series and thermally in parallelin a thermoelectric module. The module produces a direct current (DC)voltage that is a function of the properties of the materials used, thetemperature differential, the absolute temperature at which thegenerator is operated, the size of the module, and other factors. Moreinformation about thermoelectric generators is found in the relatedapplications previously incorporated herein by reference. Athermoelectric generator may have a life span of 200,000 hours, makingit suitable for long-term use without expensive replacement.

In system 100, the temperature differential between reservoir 105 andthe cooling fluid circulating through an environment-coupled piping loopis exploited to generate electricity. Fluid drawn from or heated byreservoir 105 may be circulated to a “hot” side of thermoelectricgenerator 113, while cooling fluid is circulated to a “cold” side ofthermoelectric generator 113. In some embodiments, for residential use,thermoelectric generator 113 produces about 1 kW when subjected to atemperature differential of 110° F. (61° C.). This amount of power issufficient to supply most of the electrical needs of aconservatively-managed household. The system may be scaled up as neededby adding additional capacity to reservoir 105 and additionalthermoelectric modules to thermoelectric generator 113.

While deep earth-coupled piping loop 110 is one example of anenvironment-coupled piping loop that may be used to cool the coolingfluid, the system may be further optimized by the use of other kinds ofenvironment-coupled loops as well. For example, a shallow earth-coupledloop 122 may be provided. Shallow earth-coupled piping loop 122 may beplaced, for example, within about 1.5 feet (0.5 m) of the groundsurface. During the winter, soil temperatures near the surface may besignificantly colder than the relatively constant temperature maintainedseveral feet below surface. In some places, the ground may even freezeto a depth of several inches during the winter. The temperaturedifferential experienced by thermoelectric generator 113, and thereforealso the amount of power generated by thermoelectric generator 113, maybe increased if the cooling fluid is circulated through shallowearth-coupled piping loop 122 rather than deep earth-coupled piping loop110 during times when the surface temperature is colder. Similarly,alternatively or additionally, an air-coupled piping loop 123 may beprovided. During times of extreme cold weather, air-coupled piping loop123 exposed to the atmosphere may experience temperatures even colderthan shallow earth-coupled piping loop 122, and may therefore cool thecooling fluid to an even colder temperature so that the amount of powergenerated by thermoelectric generator 113 may be even further increasedby circulating the cooling fluid through air-coupled piping loop 123.

When any of the environment-coupled piping loops is expected toexperience below-freezing temperatures, the cooling fluid circulatedthrough that loop is preferably not pure water, but may be water mixedwith anti-freeze, or another kind of fluid. It is not necessary that allof the environment-coupled piping loops be present or carry the samecooling fluid, as long as the cooling fluids can efficiently remove heatfrom thermoelectric generator 113. Typically, the cooling fluid would becirculated through only one environment-coupled piping loop at a time.In one scenario, a system controller selects which environment-coupledpiping loop to utilize at any particular time based on the temperaturesexperienced by each of them.

Because a thermoelectric generator produces DC, system 100 may includeas many appliances and other electrical devices as possible that canoperate on DC power. For example, lighting 114 may be based on lightemitting diodes (LEDs) for very efficient light production from DCpower. Many other appliances are available that operate on DC power, andit is anticipated that the number of available DC-powered applianceswill grow in the future. For those loads that can utilize DC power,system 100 preferably includes a DC power bus throughout building 109.

In the interim, some loads may still best utilize alternating current(AC) power, for example refrigerator 115. System 100 may thereforeinclude one or more inverters 116, which convert the DC output ofthermoelectric generator 113 to AC power. In some embodiments, multiplesmall inverters may be used in place of a single large-capacityinverter, so that in the event of an inverter failure, areduced-capacity system can still be operated until the failed inverteris repaired or replaced.

Backup may also be provided for the electrical portion of system 100, inthe form of a connection 117 to the mains grid, for example a publicutility. Alternatively, a local gasoline-powered or other generator maybe connected at connection 116 for emergency use or during times ofincreased electrical use, for example when hosting guests.

As is apparent from the above discussion, system 100 provides manyuseful advantages, including the use of energy stored in reservoir 105for multiple purposes, including both heating and electrical generation.Because energy is stored in reservoir 105, heating, cooling, andelectrical generation can continue even at night or during inclementweather when little or no solar radiation is available.

FIG. 1 shows also shows other optional features of system 100, inaccordance with other embodiments. Thermoelectric generator 113 maypower a hydrogen generator 118 that generates hydrogen, for example fromsupply water by means of electrolysis or another process, when power isavailable from thermoelectric generator 113. In one mode of operation,power may be diverted to the hydrogen generator overnight whenelectrical demands of building 109 are otherwise low. Hydrogen fromhydrogen generator 118 could be supplied to a hydrogen powered vehicle119, or could be stored for other uses, for example to heat domestic hotwater when backup heating is needed. Hydrogen generator 118 andassociated storage would thus provide additional energy storage utilizedduring times when reservoir 105 is at its thermal capacity and surpluspower is available from thermoelectric generator 113.

Because thermoelectric generator 113 has a finite power outputcapability, it may be helpful to manage the power demand of building109. In some embodiments, a load controller 120 may be provided thatmanages the operation of certain appliances. Load controller 120, maybe, for example, a computerized device that monitors the operation ofvarious appliances and other loads, and controls the availability ofpower to them. The effect may be time-shifting of certain loads indeference to other loads so that power is made available where needed,but the overall operation of the appliances is still satisfactory. Inone simple example of the operation of load controller 120, refrigerator115 may be prevented from operating when microwave oven 121 is inoperation. A microwave oven is an appliance that the user typicallywants to use immediately for a short time. A refrigerator operatesintermittently, and persons in the household often are not even aware ofwhether the refrigerator is running. A short delay in the operation of arefrigerator has negligible effect on its performance. Delaying theoperation of the refrigerator 115 until microwave 121 is finishedprevents both from contributing to the electrical demand at the sametime, with little or no perceived effect on the operation of eitherappliance. Potentially, this arrangement reduces the peak electricaldemand of building 109. Many other appliance timing, delay, or interlockstrategies may be envisioned. For example, the operation of a clothesdryer may be prevented while an electric range is in operation, or theintensity of lighting may be reduced to free up electrical capacity forthe operation of a hair dryer. Many other examples are possible. Inother embodiments, certain appliances may be constrained to operate onlyduring certain times of the day. For example, a clothes dryer may beallowed to operate only between 10:00 AM and 3:00 PM, when maximum solarradiation is typically available.

FIG. 2 shows a portion of system 100 in greater detail, in accordancewith another embodiment. As thermal energy is drawn from reservoir 105,whether for heating or electricity generation, the temperaturedifferential across thermoelectric generator 113 decreases, andconsequently the voltage produced by thermoelectric generator 113 alsodecreases. Certain loads may have specific voltage ranges in which theymust operate. For example, inverter 116 may require that its inputvoltage be within a certain range, or DC appliances may operate mosteffectively when supplied with power within a specified voltage range,e.g. near 36 of 48 volts. In the embodiment of FIG. 2, thermoelectricgenerator 113 comprises multiple banks 201 of thermoelectric elements.Each bank produces a portion of the electrical power available fromthermoelectric generator 113, and outputs its power on one of sets ofleads 209. A matrix switch 206 dynamically configures theinterconnections of the banks to maintain certain power characteristicsat main output leads 210. For example, when the full temperaturedifferential is available, matrix switch may configure the banks inparallel, but when the temperature differential is reduced such thateach bank produces only a fraction of the voltage it produces at fullpower, matrix switch 206 may connect the banks in series so that theoutput voltage is maintained within the required levels. Matrix switch206 may also interconnect the banks in various series and parallelcombinations as needed.

A monitor 202 senses the character of the power being produced at mainoutput leads 210, and sends a signal 203 to a controller 204, which thensignals 205 matrix switch 206 to change its interconnection. Monitor 202may measure the voltage produced at leads 210 using sensing connections207, may measure the current being supplied using a current probe 208,or may measure some other characteristic upon which to make a decisionabout the interconnection of the banks.

In this way, nearly all of the energy stored in reservoir 105 may beextracted for electricity generation. (Although the amount of availablepower may decline as the temperature of reservoir 105 declines.) Bycomparison, batteries may be restricted to supplying only 20% of theirstored energy. More detail about the operation of matrix switch 206 maybe found in the applications previously incorporated herein byreference.

The invention has now been described in detail for the purposes ofclarity and understanding. However, it will be appreciated that certainchanges and modifications may be practiced within the scope of theappended claims.

1. An integrated energy system for a building, the system comprising: atleast one reservoir of thermal energy; at least one solar collector thatprovides heat to the reservoir; at least one environment-coupled pipingloop through which a cooling fluid is circulated such that heat isexhausted from the cooling fluid to the environment; a thermoelectricgenerator that generates electric power from a temperature differentialbetween the reservoir of thermal energy and the cooling fluid; and atleast one hydronic heating unit through which heated fluid is piped,providing space heating to at least one space in the building, theheated fluid deriving its heat from the reservoir of thermal energy. 2.The integrated energy system for a building of claim 1, furthercomprising at least one hydronic cooling loop through which at leastsome of the cooling fluid is piped, providing space cooling to at leastone space in the building.
 3. The integrated energy system for abuilding of claim 1, further comprising: a backup heater that providesheat to the reservoir of thermal energy, supplementing the solarcollector.
 4. The integrated energy system for a building of claim 3,wherein the backup heater derives heat from a fossil fuel.
 5. Theintegrated energy system for a building of claim 1, further comprising atank of hot water designated for domestic hot water use.
 6. Theintegrated energy system for a building of claim 1, further comprising abackup domestic water heater that supplies heat to hot water designatedfor domestic hot water use when insufficient energy is otherwiseavailable.
 7. The integrated energy system for a building of claim 6,wherein the backup domestic water heater comprises at least oneon-demand heater.
 8. The integrated energy system for a building ofclaim 6, wherein the backup domestic water heater derives heat from afossil fuel.
 9. The integrated energy system for a building of claim 1,further comprising a direct-current power grid within the building. 10.The integrated energy system for a building of claim 1, furthercomprising an inverter that converts direct-current power from thethermoelectric generator to alternating-current power.
 11. Theintegrated energy system for a building of claim 1, wherein thethermoelectric generator comprises a plurality of banks, the integratedenergy system further comprising: a thermoelectric generator controller;and a matrix switch that, under control of the thermoelectric generatorcontroller, configures the interconnection of the banks.
 12. Theintegrated energy system for a building of claim 1, further comprising aload controller that at least temporarily prevents the operation of atleast one load based in part on the amount of electrical power beingconsumed by other loads.
 13. The integrated energy system for a buildingof claim 1, further comprising a load controller that constrains atleast one appliance to operate only during certain predetermined timeintervals.
 14. The integrated energy system for a building of claim 1,further comprising a backup connection to the mains power grid, thebackup connection providing electrical power to the building tosupplement the thermoelectric generator.
 15. The integrated energysystem for a building of claim 1, further comprising a hydrogengenerator powered by electricity from the thermoelectric generator. 16.The integrated energy system for a building of claim 15, furthercomprising a backup domestic water heater, and wherein the backupdomestic water heater derives heat from hydrogen generated by thehydrogen generator.
 17. The integrated energy system for a building ofclaim 1, wherein the reservoir of thermal energy comprises a tank ofheated water.
 18. The integrated energy system for a building of claim1, wherein a medium in the reservoir of thermal energy is heateddirectly by the solar collector.
 19. The integrated energy system for abuilding of claim 1, wherein a medium in the reservoir of thermal energyis heated though a heat exchanger carrying a second medium heated by thesolar collector.
 20. The integrated energy system for a building ofclaim 1, wherein the heated fluid circulated through the at least onehydronic heating unit derives its heat from the reservoir of thermalenergy through a heat exchanger.
 21. The integrated energy system for abuilding of claim 1, wherein the at least one environment-coupled pipingloop comprises a deep earth-coupled piping loop.
 22. The integratedenergy system for a building of claim 1, wherein the at least oneenvironment-coupled piping loop comprises a shallow earth-coupled pipingloop.
 23. The integrated energy system for a building of claim 1,wherein the at least one environment-coupled piping loop comprises anair-coupled piping loop.
 24. A method of operating an energy system in abuilding, the method comprising: heating a reservoir of thermal energyusing a solar collector; circulating heated fluid through a hydronicheating loop, providing space heating to at least one space in thebuilding, the heated fluid deriving its heat from the reservoir ofthermal energy; circulating a cooling fluid through anenvironment-coupled piping loop such that heat is exhausted from thecooling fluid to the environment; and generating electrical power in athermoelectric generator subjected to a temperature differential betweenreservoir and the cooling fluid.
 25. The method of operating an energysystem in a building of claim 24, further comprising: circulating atleast some of the cooling fluid through a hydronic cooling loop,providing space cooling to at least one space in the building.
 26. Themethod of operating an energy system in a building of claim 24, furthercomprising: generating hydrogen using electrical energy generated by thethermoelectric generator.
 27. The method of operating an energy systemin a building of claim 24, further comprising: storing, separately fromthe reservoir of thermal energy, water designated for domestic hot wateruse.
 28. The method of operating an energy system in a building of claim27, further comprising heating the water designated for domestic hotwater use with heat from the reservoir of thermal energy.
 29. The methodof operating an energy system in a building of claim 24, furthercomprising dynamically configuring, using a thermoelectric generatorcontroller, interconnections of thermoelectric modules within thethermoelectric generator.
 30. The method of operating an energy systemin a building of claim 24, further comprising temporarily preventing theoperation of at least one electrical load based in part on the amount ofelectrical power being consumed by other loads.
 31. The method ofoperating an energy system of claim 24, wherein circulating the coolingfluid through an environment-coupled piping loop comprises circulatingthe cooling fluid through an earth-coupled piping loop.